Grant: Idea to Innovation

With the ageing population hip replacement surgery is a growing field. As the life expectancy of these patients increases, the chance of a revision surgery also increases. During revision surgery, the greater trochanter (a bony protrusion on the upper outside part of thigh bone (femur)) must often be removed for adequate access to the existing implant and hip socket. Currently, there are several systems to reattach the greater trochanter but there are still many complications. For example, the fracture may not completely heal because of small movements and swelling and irritation common because the implant is too bulky. The objective of this research project is to design a new greater trochanter fixation system (Y3-SMA) consisting of a Y shaped plate and superelastic cables. This project will be done in 5 steps. First a 3D computer model of the femur and an existing implant (Zimmer Cable-Ready?, Warsaw IN) will be built and validated. Then this model will be adapted to virtually test and optimize the new Y3 plate design as well as to evaluate characteristics of the SMA superelastic cables. The new Y3 plate will be made from the results of this model. At the same time, new SMA superelastic cables will be braided from shape memory alloy thread. These threads have a built in elasticity so that once stretched they spring back and continue to apply compressive force instead of becoming slack. Because of this, the SMA cables are capable of maintaining a constant compression between the fractured piece and the rest of the bone. Once these systems are made, they will be tested on artificial bone models of the femur. The testing will represent the muscles pulling on the greater trochanter fragment. An existing system and the new Y3-SMA system will be compared. The anticipated results will show that the low-profile Y3-SMA system better resists the muscle forces therefore reducing undesirable movement, swelling and pain.